Visit the Elimina Castles Cape Coast which really do offer a first hand experience of what the slave trade was like from all sides involved. Its a tour you have to take to really get an understanding of this deep history.
“Elmina Castle was erected byPortuguese in 1482 as São Jorge da Mina (St. George of the Mine) Castle, also known simply as Mina or Feitoria da Mina) in present-day Elmina, Ghana(formerly the Gold Coast). It was the first trading post built on the Gulf of Guinea, so is the oldest European building in existence below the Sahara”. (wiki)